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Microbiology 2100 > Central Dogma and Polio > Flashcards

Central Dogma and Polio Flashcards

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Biology 101 flashcards
1
Q

what are viruses?

A

obligate intracellular parasites

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2
Q

what are the 2 was viruses can use host resources / machinery?

A
  1. conform themselves to fit host machinery

2. conform host machinery to fit them

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3
Q

DNA dependent DNA polymerase uses ___ to make ___

A

dsDNA; more dsDNA

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4
Q

RNA polymerase uses ___ to make ___

A

dsDNA ; (+) ssRNA

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5
Q

ribosomes translate +ssRNA into ___

A

amino acid sequence

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6
Q

T/F virus genomes can be DNA or RNA

A

true

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7
Q

the genomes of viruses can be diverse, but all most pass through a stage that resembles ___

A

mRNA

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8
Q

why must all viruses go through a stage of resembling mRNA?

A

host protein synthesis can use it to make viral protein

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9
Q

gene products (mostly proteins) are required for what 5 things?

A
  1. replication of viral genome
  2. assembly and packaging of genome particles
  3. regulation and timing of replication cycle
  4. modulation of host defence
  5. spread to other cells and hosts
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10
Q

what information is encoded by viral genomes?

A

protein products

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11
Q

do viral genomes encode the complete protein synthesis machinery?

A

no

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12
Q

do viral genomes encode proteins involved in energy production and membrane synthesis? [

A

no

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13
Q

do viral genomes encode centromeres or telomeres?

A

no

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14
Q

+ ssRNA viruses get directly translated into the cytoplasm (T/F)

A

ture

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15
Q

how do polioviruses express their genes?

A

direct translation into cytoplasm

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16
Q

how do polioviruses replicate their genomes?

A

viral RNA dependent RNA polymerase with dsDNA intermediates

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17
Q

why don’t Polioviruses use host RNA dependent RNA polymerase?

A

because host cells don’t have them!

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18
Q

would progeny viruses be made if naked RNA into a host cell? Why/why not?

A

yes because the genome is already translated

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19
Q

the amino terminal makes a lot of ___ proteins

A

structural

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20
Q

the carboxyl terminal makes a lot of ___ proteins

A

enzymatic

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21
Q

T/F polyproteins can be cleaved by either host or viral proteases into the full complement of viral proteins

A

true

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22
Q

why do proteases make a good drug target? (2)

A
  1. if proteins are not made, the virus can’t replicate

2. unique (not going to accidentally target host)

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23
Q

disadvantage for virus relying on host proteases?

A

host is in control

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24
Q

poliovirus and HCV both encode RNA dependent RNA polymerase at which end of the genome?

A

3’

25
Q

why is there an RNA dependent rna polymerase on the 3’ end of the polio genome?

A

it puts it in the perfect spot to bind to the rna and and start replication in the 5’ direction to make the complementary strand

26
Q

T/F RDRP (rna dependent rna polymerase) is a drug target

A

true

27
Q

the poliovirus causes what disease?

A

poliomyelitis

28
Q

where does poliovirus live?

A

in the water

29
Q

t/f the infection of poliomyelitis used to be common, but the infection was not

A

true

30
Q

__% of cases of poliomyelitis are asymptomatic

A

95

31
Q

__% of poliomyelitis cases spread to secondary tissues and cause flu-like symptoms

A

5

32
Q

__% of poliomyelitis cases enter the central nervous system and results in selective destruction of motor neurone

A

less than 1

33
Q

what are the 2 effective vaccines for poliomyelitis?

A
  1. sabin (oral)

2. stalk (intradermal)

34
Q

how is the poliovirus grown and inactivated to make the stalk vaccine?

A

grown in kidneys of monkeys; inactivated by formalin

35
Q

how is the poliovirus grown and attenuated in the sabin vaccine?

A

grown at subphysiologic temperatures, which causes the virus to undergo spontaneous mutations

36
Q

t/f the attenuated poliovirus of the oral sabin vaccine can replicate in the gut

A

t

37
Q

the oral Sabin vaccine establishes what type of immunity?

A

mucosal

38
Q

what makes the erradication of poliomyelitis possible?

A

no animal reservoir

39
Q

poliovirus binds to what receptor on the cell surface of a host?

A

CD155 (PVR)

40
Q

what is the normal function of CD155 PVR?

A

cel-cell contact between epithelial cells

41
Q

once bound to the PVR, how does the poliovirus enter the host cell?

A

endocytosis

42
Q

once endocytized, the capsid of the poliovirus is ___ and releases __ into the cytoplasm

A

destabilized; +ssrna

43
Q

what is the capsid shape of the poliovirus?

A

icosahedral

44
Q

the icosohedral shape of the capsid of poliovirus allows it to survive __

A

the acidic pH of gut

45
Q

the +ssrna of poliovirus is translated by __ to make a __

A

host ribosomes; polyprotein

46
Q

viral and host proteases process polyprotein into ___ and __

A

capsid proteins and machinery for proteases and rna synthesis

47
Q

t/f polyprotein translation if cotranslational

A

t

48
Q

during polyprotein processing, as soon as viral protease is made, cleavage happens immediately, this is called __

A

auto proteolysis

49
Q

auto proteolysis in processing poliovirus is due in part to __

A

viral enzymes acting in cis on the same molecule

50
Q

__ is the viral rna dependent rna polymerase

A

3D

51
Q

3d uses +ssrna as a template to make __ in the ___ direction

A

-ssrna; 3’-5’

52
Q

3d makes a __ intermediate

A

ds rna

53
Q

ds rna is the template for __

A

+ssrna progeny genome

54
Q

in order to make +ssrna progeny from +rna, the rna polymerase first has to make the __

A

mirror image

55
Q

what is a disadvantage of having an rna dependent polymerase?

A

sets off host recognition receptors

56
Q

what is Ribavirin?

A

an inactive pro-drug which is phosphorylated and activated within cells

57
Q

ribavirin is an analogue for __ and can therefore bind to

A

adenine and guanine ; cytosine, uracil

58
Q

ribavirin induces ___ viruses, which can be lethal to rna viruses

A

hypermutation

59
Q

t/f ribavirin can be incorporated into viral rna during genome replication

A

t

Microbiology 2100 (26 decks)

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